The present invention relates to an apparatus, system and method of feeding flat articles to a sorter, and in particular, feeding mail items to an automated mail processing machine such as a mail sorter.
Modern postal services, for example, the U.S. Postal Service, handle massive volumes of mail pieces on a daily basis. Machines for receiving and sorting these massive volumes of letter mail are known. Typically, such machines are adapted to receive large volumes of flat articles and sort the articles into a plurality of pockets or bins based upon selected criteria. In the case of letter mail, the criteria is associated with the destination of the individual mail pieces which may be an indicia such as a Zip+4 destination code. Typically, such sorting machines have a feeding station, sensing and detecting equipment for determining the appropriate output compartment or pocket for the article to be sorted and diverting gates or other mechanisms for selectively diverting articles to selected ones of an array of output compartments or pockets for the sorted articles. An example of an advanced sorting machine is the DBCS sorting device, available from Siemens ElectroCom, L.P., Arlington, Tex.
Devices for singulating and feeding mail pieces to a sorting machine are known. One such apparatus is disclosed in U.S. Pat. No. 5,947,468, the disclosure of which is incorporated by reference for all purposes. Such devices however, do not meet all the existing needs in terms of processing different types of flat articles. Ideally, the feeder/singulator of a mail sorting machine as described above would have the capability of handling stacks of flat articles of varying thickness while maximizing throughput. However, feeding and singulating a stack of flat articles including thin flat items such as letters, and thicker packages such as packaged catalogues, for example up to xc2xd inch, presents a number of difficulties. For example, when thick flat articles are fed one-by-one from a stack of flat articles, the volume of the stack is reduced rapidly. Conversely, when thin, flat articles are fed, the volume of the stack is reduced at a much slower rate. Existing feeder/singulation methods and apparatus do not provide for feeding a stack of flat articles having varying thicknesses, such as mail pieces, while simultaneously maximizing throughput. The present invention addresses this drawback.
In one aspect, the invention comprises a method of singulating and feeding a random mix of thick and thin flat articles including: (a) sensing whether a flat article is positioned on a feed conveyor in a position for removal from the feeder conveyor with a sensor, (b) advancing the feed conveyor an incremental step with a first motor to place a series of flat articles positioned on edge in a position for removal from the feed conveyor each time the sensor detects the absence of a flat article for removal from the feed conveyor, (c) counting each incremental advance of the feed conveyor, (d) incrementally advancing the stack of flat articles with a jogger driven by a second motor after the feed conveyor has moved a predetermined number of incremental steps to load additional flat articles on the feed conveyor, the jogger tending to edge the flat articles for removal from the feed conveyor; and (e) repeating steps (a)-(d) while sequentially removing flat articles from the feed conveyor on a one-by-one basis as the feed conveyor is advanced. The method is implemented with a feeder comprising a belt type feeder conveyor, a chain driven, finger type jogger and a belt type staging conveyor where the flat articles and/or mail pieces are loaded edgewise. The stack of mail pieces is advanced from the staging conveyor to the jogger and then to the feed conveyor from which the flat articles are removed with a take off device, such as a vacuum assisted belt conveyor oriented perpendicular to the feed conveyor. The staging conveyor, jogger and feed conveyor are each provided with a separate drive motor, allowing each to be controlled independently and operated at a different speed, which in turn allows dynamic control of the feeder system. The jogger motor is energized after the feed conveyor motor turns a predetermined number, for example 6-8 xe2x80x9cticksxe2x80x9d i.e., rotations or fractional rotations of the motor that are registered and counted with an internal clock like sensor. The number of ticks required to activate the jogger will depend upon the particular design of the feeder system, including the relative linear velocities of feeder conveyor 16 and jogger 16, the spacing of the jogger fingers and other criteria specific to a particular application. After the jogger is activated, it advances until a jogger finger sensor detects a jogger finger moving into proximity to a jogger finger sensor at which time the jogger motor is deactivated, stopping the jogger.
In this aspect, the method includes loading the staging conveyor with flat articles and incrementally advancing the stack with the staging conveyor to load additional flat articles on the jogger after the feed conveyor has moved a predetermined number of incremental steps. When the staging conveyor is loaded, a paddle is placed at the end of the stack to hold the stack as it is carried to the jogger. The staging conveyor is preferably provided with a series of centrally positioned perforations or holes that extend the length of the conveyor into which a tab or projection of the paddle is inserted so the staging conveyor carries the paddle as it advances. The feeder is also equipped with one or more paddle sensors which detect the paddle as it moves to different locations such as a staging paddle sensor that senses the paddle as it approaches the end of the staging conveyor and signals the feeder controller to deactivate the unit until the staging is reloaded with addition flat articles.
In another aspect, the jogger imparts a bouncing motion to the stack of articles as it carries the articles to the feed conveyor. The bouncing motion is imparted with one or more shafts having at least one flattened surface that rotate between the fingers of the jogger. The bouncing motion of the jogger tends to separate and edge or align the flat articles vertically and horizontally as the articles are conveyed. Stack separation fingers, driven by the jogger create temporary gaps in the stack as the stack is conveyed from the staging conveyor to the jogger. The separation fingers are preferably actuated with a rotary cam driven by the jogger, however, the operation of the separation fingers could be initiated with a sensor or timer depending upon the particular design and application.
In yet another aspect, according to the invention, a feeder for a mail sorter includes a controller, a horizontal entry belt conveyor, a jogger which receives a stack of mail from the entry conveyor on edge and aligns the stack as it passes through the jogger and a horizontal feeder belt conveyor that receives the stack in increments from the jogger. An upright take off mechanism at an end of the feeder conveyor opposite the jogger sequentially removes the frontmost mail piece from the stack, conveying each piece sideways and feeding a singulated stream of mail pieces to the mail sorter. A repositionable paddle mounted on a rail above the conveyors and jogger supports a rear end of the stack of mail pieces as it moves through the feeder. A plurality of paddle sensors each signal the controller when the paddle is in proximity of the sensor. In particular a paddle sensor positioned adjacent to the end of the entry conveyor signals the controller to shut the feeder down when the paddle reaches the sensor.
Operation of the feed conveyor is controlled with a switch positioned adjacent to the take off device that determines when a frontmost mail piece is in sufficient engagement with the take off mechanism for the take off mechanism to remove the frontmost mail piece from a stack of mail. When a mail piece is not present, the feed conveyor motor is cyclically advanced in increments until the foremost mail piece is detected. A sensor or switch associated with the feeder conveyor motor signals the controller that counts each incremental advance of the feeder conveyor and incrementally advances the jogger to feed additional mail pieces onto the feeder conveyor when a predetermined number of incremental advances of the feeder conveyor has occurred. In a preferred embodiment, the take off mechanism comprises a vertical belt type conveyor and a jogger sensor is provided for detecting an incremental movement of the jogger.